docs: def quaternion_multiply(quaternion1, quaternion0):
      """Return multiplication of two quaternions.
  
      >>> q = quaternion_multiply([4, 1, -2, 3], [8, -5, 6, 7])
      >>> numpy.allclose(q, [28, -44, -14, 48])
      True
  
      """
      w0, x0, y0, z0 = quaternion0
      w1, x1, y1, z1 = quaternion1
      return numpy.array([-x1*x0 - y1*y0 - z1*z0 + w1*w0,
                           x1*w0 + y1*z0 - z1*y0 + w1*x0,
                          -x1*z0 + y1*w0 + z1*x0 + w1*y0,
                           x1*y0 - y1*x0 + z1*w0 + w1*z0], dtype=numpy.float64)